It is known, for example from British Patent Specification No. 1,530,799, to use mixture of tripolyphosphate and orthophosphate in detergent compositions. In particular, these compositions may comprise from 5% to 30% of a synthetic anionic, nonionic, amphoteric or zwitterionic detergent compound or a mixture thereof, and from 10% to 30% of mixed alkali metal tripolyphosphate and alkali metal orthophosphate in the ratio of from 10:1 to 1:5 parts by weight, wherein the amount of alkali metal tripolyphosphate is at least 5%, and the amount of any alkali metal pyrophosphate is not more than 5%, all these percentages being by weight of the total detergent composition, and the pH of a 0.1% aqueous solution of the composition is from 9 to 11.
It is also known, for example from British Patent Specification No. 1,536,136, to incorporate polyelectrolytes such as substituted polyacrylic acids in detergent compositions for the purposes of lowering the amount of insoluble inorganic material which becomes deposited on the fabric during washing.